1. Technical Field
The present invention relates to a method for suspending food particulates in a food sauce and, in particular, the suspension of fruit pieces in a sauce while preserving the fresh fruit presentation. The method can also be used to produce food products having a semi-fluid matrix with a pulpy, grainy, stringy, or beady texture. The method involves manipulating a low methoxyl pectin pre-gel by controlling various chemical and physical reactions.
2. Description of Related Art
Sauces containing a cooked fruit suspension are common in the prior art. These include various jam and jelly preparations, as well as other cooked fruit sauces, such as apple sauce, and other products containing fruit pieces in suspension. Typically, the fruit and a gelling agent are mixed at a high temperature in order to avoid the formation of a pre-gel prior to the introduction of fruit pieces into the mixture. As the entire mixture cools, the gelling agent begins to provide a media for the suspension of the cooked food particles. A gelation of the gelling agent prior to complete mixing of the final product is considered undesirable in the prior art, as such early gelation (or pre-gel) causes a lumpy texture, as opposed to a smooth texture, to the final product.
Pectins are frequently used as gelling agents in food products. Pectin is the methylated ester of polygalacturonic acid, and is generally divided into two categories of either high methoxyl pectin or low methoxyl pectin. Pectin is a long-chain molecule comprising a series of 300 to 1,000 rings of glalacturonic acid connected in a linear series. Some of these glalacturonic acid units are in the methyl ester form, while the other units are in the acid form. The ratio of the units found in the methyl ester form to the total units is expressed as a degree of methoxylation, or degree of esterification, which terms are typically abbreviated as “DM” or “DE,” respectively. Any pectin having a DE of 50% or greater is considered a high methoxyl pectin, while any pectin having a DE of 50% or lower is considered a low methoxyl pectin. The two types of pectins have different gelling characteristics and, consequently, are used typically in different applications. For example, low methoxyl pectins are susceptible to gelation in the presence of divalent ions, such as calcium ions found in fruits. Conversely, high methoxyl pectin does not gel in the presence of divalent ions such as calcium.
As a consequence of low methoxyl pectins gelling reactivity with calcium, it is avoided in the prior art as a gelling agent for fruit suspensions. As noted by U.S. Pat. No. 4,370,354, titled “Stabilized Fruit Suspensions and Method for Preparing the Same,” issued to Leipold (the '354 Patent), the use “of low methoxyl pectin as the gelling agent is attended by certain difficulties resulting from the fact that it is calcium sensitive and in the presence of calcium tends to form stiffer gels than are desired. One difficulty is that all fruits contain calcium.” (Col. 1, lns. 27–31). As further noted in the '354 Patent, this difficulty can be overcome by adding an excess of calcium over the amount which can react with the pectin. This is done while the pectin is maintained at a high temperature such that the pectin fully reacts with the added calcium prior to the addition of the fruit to be suspended. The final mixture is then further cooked and then slowly cooled in order to avoid the formation of any pre-gel.
Low methoxyl pectins are desirable in many instances over high methoxyl pectins as a gelling agent, however, because high methoxyl pectins require as a condition for gellation a pH of 3.5 or lower and high solids. Typically, low methoxyl pectins can form a gel in a pH range of 1.0 to 7.0 or higher in a low to medium solids food product. Nonetheless, all of the prior art, including the '354 Patent, teaches that the low methoxyl pectin and fruit mixture must occur at a high temperature to avoid pre-gel.
Difficulties arise when it is desirable to produce a food sauce that has a fresh fruit taste and texture, as opposed to the cooked fruit taste and texture of jellies, jams, and other prior art fruit suspensions and sauces. The prior art teaches that low methoxyl pectin is a desirable gelling agent. However, the prior art further teaches that low methoxyl pectin must be kept at a high temperature, for example, above 150° F., throughout the preparation of the food sauce in order to avoid large lumps created by pre-gel. This elevated temperature cooks the fruit in situ and precludes the presentation of a fresh fruit sauce or suspension.
It would be desirable to develop one or more methods of producing a food sauce comprising, for example, an uncooked fruit suspension that gives a fresh fruit mouth feel and taste. Ideally, such process should allow for the use of a low methoxyl pectin as the primary gelling agent while controlling the pre-gel of the low methoxyl pectin in order to enhance the presentation of the final product. Further, the method should be susceptible to implementation by existing food technology equipment and provide for an economical method for producing a desirable food presentation.